Dr Medhat Abbas, head of the crisis management unit at the health ministry in Gaza, said that electricity from generators would only be available for a few more hours at the Al-Nasser children's hospital.

In video

-Jacky Rowland reports on the impact of the Gaza blockade- Nour Odeh reports on the pressure mounting on the Palestinian president"These patients and these children are facing their destiny and they will die soon," he told Al Jazeera.

"They escaped from their poor houses were they have very cold weather ... The families brought them here to be saved in the incubator. Now the incubator and the nursery will be out of electricity.

"What sort of humanitarian law is this?"

He said the blackout would also deprive cancer and intensive care patients of their treatment as well as spoiling blood and vaccines that were being stored.

Al Jazeera's Jacky Rowland in Gaza said that it was not only power generation that would be affected.

"It also means no fuel for the generators that fuel the water pumps - a lot of the water in Gaza is deep beneath the surface, and it has to be pumped to the surface - so no fuel can also mean no water."

'Collective punishment'

The UN has said Israel should not collectively punish Gaza's population while responding to security threats.

The organisation has criticised Israel's decision to close border crossings into Gaza, preventing aid deliveries to the 1.5 million people living in the territory, saying on Saturday that the move could provoke a humanitarian crisis.

Palestinians fear the power cut could bedisastrous for the health sector [AFP]Ban Ki-moon, the UN secretary-general, also urged an immediate end to violence in Gaza and Palestinian sniper and rocket attacks into Israel.

Zeev Boim, an Israeli cabinet minister, said that rather than condemning Israel's move, the UN should condemn Palestinian rocket attacks.

"I don't hear the UN's voice," he said.

Israel has continued to push ahead with its military offensive against Palestinian fighters in both Gaza and the West Bank in recent days.

Late on Sunday, an Israeli air raid killed at least one Palestinian and critically wounded another in the northern Gaza Strip. Hamas officials said that the target was a group of fighters who launched makeshift rockets into southern Israel.

Around 230 such rockets and mortars have been fired over the border since Tuesday, according to the Israeli military. At least 36 Gazans have been killed by Israeli fire in the past week.Source: Al Jazeera and agencies